Enhanced flux pinning in YBCO multilayer films with BCO nanodots and segmented BZO nanorods

The flux pinning properties of the high temperature superconductor YBa₂Cu₃O_7-δ (YBCO) have been conventionally improved by creating both columnar and dot-like pinning centres into the YBCO matrix. To study the effects of differently doped multilayer structures on pinning, several samples consisting of a multiple number of individually BaZrO₃ (BZO) and BaCeO₃ (BCO) doped YBCO layers were fabricated. In the YBCO matrix, BZO forms columnar and BCO dot-like defects. The multilayer structure improves pinning capability throughout the whole angular range, giving rise to a high critical current density, J _c. However, the BZO doped monolayer reference still has the most isotropic J _c. Even though BZO forms nanorods, in this work the samples with multiple thin layers do not exhibit a c axis peak in the angular dependence of J _c. The angular dependencies and the approximately correct magnitude of J _c were also verified using a molecular dynamics simulation.